Split die tube bending apparatus

ABSTRACT

A tube bending apparatus having an interior bending die about which a tubular segment having fittings on each end that would normally preclude bending to approximately 180 degrees is bent, the interior bending die being separable into two portions along the bending plane, such that the die can be split to release the bent tubular member.

This application claims the benefit of U.S. Provisional Patent SerialNo. 60/624,045, filed Nov. 1, 2004, the disclosure of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates generally to the field of tube bendingapparatuses and the dies used therein, and more particularly to suchapparatuses and dies that are used in bending thin-walled, smalldiameter metal tubes, and to the methodology used in accomplishing thebending of the tubes.

Apparatuses for bending metal tubes without crimping or deforming thecircular cross-section of the tubes are well known. For the bending ofthin-walled, small diameter metal tubes made of aluminum or similarmetal, relatively small apparatuses have been developed and are oftenpowered hydraulically. An example of such an apparatus is shown in myU.S. Pat. No. 5,237,847, issued on Aug. 24, 1993, the disclosure ofwhich is hereby incorporated by reference. With this type of tubebending apparatus, a generally semi-circular bending shoe or die isadvanced by a hydraulic cylinder between a pair of circular bendingrollers or dies, with the tube to be bent disposed there between. Inother types of tube bending apparatuses, one end of the tube is abuttedagainst a stop member and the bending dies are pivoted in a curved pathto accomplish the bending of the tube, or one bending die is pivotedabout a fixed die.

A drawback to these known tube bending apparatuses is that a minimumlength of unobstructed tube must be present in order to accomplish achosen bend, since the dies must be free to traverse the tube.Furthermore, for short tubes where fittings, connectors, beads, flaresor the like that extend outwardly from the tube are already connected orformed on each end of the tube, bends close to 180 degrees cannot beaccomplished because the fittings, etc. preclude removal of the tubefrom the bending die located on the interior of the bend after the bendis imparted in the tube. Because of this, short tubes with fittings orthe like are manufactured by first bending the short tube section, thenattaching the fittings using braising, welding, mechanical interlockingor similar techniques. The final products so manufactured are moresusceptible to failure because of the inherent weaknesses in the joiningmethods.

It is an object of this invention to provide an apparatus and methodthat enables the bending to and beyond 180 degrees of a short segment ofthin-walled, small diameter tubing upon which fittings, connectors,beads, flares or the like that extend outwardly from the tube arealready connected or formed on each end. It is an object to provide suchan apparatus and method whereby a short tube segment can be machined orformed such that the tube and the fittings, connectors, beads, flares,etc. are an integral, one-piece member.

SUMMARY OF THE INVENTION

Manual or powered apparatuses using dies, also known as rollers orshoes, to receive or retain a portion of a tube and which impart a bendor curve in the tube are generally known in the art. The invention is atube-bending split die and an apparatus and method for bending shortsegments of metal tubing utilizing such split die, suitable but notlimited to the bending of thin-walled, small diameter, metal tubing,wherein the bending is accomplished by utilizing an interior bending dieabout which the tube is bent to form a permanent curve or bend in thetube. In a preferred embodiment, an exterior bending die is disposed intandem with the interior bending die, such that the tube is disposedbetween the two dies and the entire cross-sectional circumference of thetube is completely enclosed within the combined generally semi-circularchannels of the two dies. The dies are preferably annular and arepreferably mounted on shafts that allow both dies to rotate during thebending operation, such that the tube-receiving channels are completelyannular in the plane perpendicular to the rotational axis.

The interior bending die is a split die constructed such that it isseparable into two halves along the bending plane, i.e., the planeperpendicular to the rotational axis disposed at the mid-point of thetube-receiving channel. In this manner, when a short tube is bent tosuch a degree that the fittings or other obstructions on the ends of thetube preclude withdrawal of the interior bending die from the tube in alinear manner, the interior split die can be separated in the axialdirection to release the bent tube.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration showing a straight, one-piece tube and fittingcombination disposed between an interior bending die and an exteriorbending die incorporated as part of a representative tube bendingapparatus.

FIG. 2 is a view taken along line II-II of FIG. 1 along the tube axis,with the tube shown in cross-section.

FIG. 3 shows the tube now having a bend of 180 degrees, such that theinterior bending die is entrapped by the fittings.

FIG. 4 is a lateral view showing the interior bending die entrapped bythe fittings.

FIG. 5 is a view similar to FIG. 4, showing the interior bending dieseparated into halves for release of the bent tube.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawings the invention will now be described indetail with regard for the best mode and the preferred embodiments. Ingeneral, the invention comprises a split tube-bending die, and inparticular a split interior tube-bending die, and the tube bendingapparatus and method incorporating such a split interior tube-bendingdie.

As represented in the figures, the work piece to be bent is a relativelyshort, tubular member 10 that as shown comprises a short, thin-walled,tube segment 11 that is linear or only slightly curved in thepre-working state. Obstructive members shown generally as fittings orconnectors 12 are disposed on each end of the tube segment, it beingunderstood that the fittings 12, as the term is used and illustratedherein, is intended to represent and include any fittings, connectors,beads, flanges or similar obstructive devices that extend outwardly fromthe surface of the tube segment 11, i.e., any obstructive member thathas a increased radius or any extensions that extend radially above thetube outer surface. The apparatus and methodology are capable of workinga tubular member 10 wherein the fittings 12 are joined to the tubesegment 12 by any known connecting techniques, such as braising,welding, bonding, mechanical interlocking or the like, or wherein thefittings 12 and tube segment 11 are formed or machined as a one-piece,integral tubular member 10.

Bending dies 20 and 30 are disposed in cooperating or mating manner suchthat the dies 20 and 30 encompass a portion of the tube segment 11 atthe point where bending is to be imparted. The bending dies 20 and 30are mounted to frames, blocks or the like that form part of a tubebending apparatus, which may be of any known type, manual or powered,suitable for bending tubular members. Use of an interior bending die 20and an exterior bending die 30 in this configuration is well knownwithin the field of tube bending apparatuses, such that as exteriorbending die 30 is manipulated about the interior bending die 20 relativeto the tubular member 10, one of the ends of the tubular member 10remaining fixed, the tube segment 11 will be bent about interior bendingdie 20. As illustrated in FIGS. 1 and 3, a representative tube bendingapparatus 100 is shown, the apparatus 100 comprising a base member 101,a locking arm 102 and a bending arm 103. The interior bending die 20 ismounted onto the base 101 on a shaft 21 such that rotation of thebending die 20 is allowed. The bending arm 103 is pivotally mounted tothe base 101 on shaft 21, such that bending arm 102 pivots about thelongitudinal axis of shaft 21 and bending die 20. The exterior bendingdie 30 is connected by shaft 31 to the end of locking arm 102, whichpivots relative to the bending arm 103, such that with a tube 11disposed in the interior bending die 20 the exterior bending die 30 canbe pivoted into abutting relation with the interior bending die 20 toencircle the tube 11. To bend the tube 11, the bending arm 103 isrotated relative to the base member 101, such that the exterior bendingdie 30 rotates about the interior bending die 20, as seen in FIG. 3.

The bending dies 20 and 30 as shown are of essentially similarconfiguration, but it is contemplated that the dies could vary inconfiguration without exceeding the bounds of the invention. Forexample, one or both of dies 20 and 30 could be only partially annular,such that the channels 22 and/or 32 do not extend a full 360 degrees.Likewise, the dies 20 and 30 could be non-annular such that channels 22and 32 are non-annular. Exterior bending die 30 as shown preferablycomprises an annular member having a tube-receiving channel 32,substantially semi-circular in the direction perpendicular to thebending plane, bounded by a pair of flanges 33 mounted on a s shaft 31such that the exterior bending die 30 will rotate about the longitudinalaxis of shaft 31, the longitudinal axis being perpendicular to thebending plane.

Interior bending die 20 as shown is similar in configuration to exteriorbending die 30, preferably comprising an annular member having atube-receiving channel 22, substantially semi-circular in the directionperpendicular to the bending plane, bounded by a pair of flanges 23.Interior bending die 20 is a split die, separable in the directionperpendicular to the bending plane, i.e., a plane perpendicular to thelongitudinal axis of shaft 21, into a first divided portion or half 24comprising a portion of tube-receiving channel 22 and one flange 23 anda second divided portion or half 25 comprising the remaining portion oftube-receiving channel 22 and the other flange 23, such that interfacesurfaces 26 are created in the middle of the annular channel 22 betweenthe flanges 23, as seen in FIG. 5. The divided portions 25 and 26 aremounted on shaft 21, such that the interior bending die 20 will rotateabout the longitudinal axis of shaft 21, the longitudinal axis beingperpendicular to the bending plane and parallel to the longitudinal axisof the exterior bending die 3. Alternatively, the shaft 21 may bedivided, with the shaft portions sharing a common longitudinal axis.Preferably, split die securing means, such as an insert member 27, suchas a pin, post, key or the like, constructed to mate with an insertcavity 27 of corresponding configuration, are provided to better secureand align the first and second divided portions 24 and 25 during thebending operation. As shown in the drawings, the divided portion 24 isseparable from divided portion 25 in the axial direction, either suchthat the divided portion 24 is completely removable from shaft 21, isable to be moved axially along shaft 21 a sufficient distance to freetube 11 after bending, or, in the case of a divided shaft 21, thedivided portion 24 and its shaft portion is separable.

To bend the tubular member 10, the tube segment 11 is disposed betweenthe bending dies 20 and 30, as shown in FIG. 1, and the tube segment 11is bent to the desired configuration, shown as a bend of 180 degreesabout the interior die member 20 in FIG. 3, by pivoting the bending arm103 relative to the base member 101 and interior bending die 20. Asshown in FIGS. 3 and 4, even if exterior bending die 30 is removed, thefittings 12 prevent removal of the tubular member 10 from the interiorbending die 20, since the flanges 23 cannot pass between the fittings 12as they are now disposed adjacent to each other in the bentconfiguration. To release the bent tubular member 10, the first andsecond divided portions 24 and 25 of interior bending die 20 areseparated in the axial direction, as shown in FIG. 5. This allows thebent tube member 10 to be released from the remaining divided portion 24or 25 since the fittings 12 are no longer restricted by the combinationof flanges 23.

It is understood that equivalents and substitutions for certain elementsand components set forth above may be obvious to those skilled in theart, and thus the true scope and definition of the invention is to be asset forth in the following claims.

1. In a tube bending apparatus comprising an interior bending die aboutwhich a tube is bent within a bending plane, the improvement comprisingsaid interior bending die being a split die, such that said interiorbending die can be separated in the direction perpendicular to saidbending plane to release said tube.
 2. The apparatus of claim 1, whereinsaid interior bending die comprises divided portions, each said dividedportion mounted onto a shaft.
 3. The apparatus of claim 2, wherein saidinterior bending die further comprises a tube-receiving channelsubstantially semi-circular in the direction perpendicular to saidbending plane.
 4. The apparatus of claim 3, wherein said tube-receivingchannel is annular.
 5. The apparatus of claim 2, said tube bendingapparatus further comprising an exterior bending die, wherein saidinterior bending die cooperates with said exterior bending die duringthe bending operation.
 6. The apparatus of claim 3, said tube bendingapparatus further comprising an exterior bending die comprising atube-receiving channel substantially semi-circular in the directionperpendicular to said bending plane, wherein said interior bending diecooperates with said exterior bending die during the bending operationsuch that the combination of said exterior bending die tube-receivingchannel and said interior bending die tube-receiving channel completelyencircles said tube.
 7. The apparatus of claim 2, further comprisingmeans to secure and align said divided portions of said interior bendingdie to each other.
 8. The apparatus of claim 7, wherein said securingand aligning means comprises an insert member disposed in one of saiddivided portions and an insert cavity disposed in the other of saiddivided portions, said insert member being received by said insertcavity when said divided portions are adjoining.
 9. A tube bendingapparatus comprising an interior bending die about which a tube is bentwithin a bending plane, said interior bending die comprising atube-receiving channel, the improvement comprising said interior bendingdie being a split die, such that said interior bending die can beseparated into divided portions in the direction perpendicular to saidbending plane to release said tube.
 10. The apparatus of claim 9,wherein each said divided portion is mounted onto a shaft.
 11. Theapparatus of claim 9, wherein said tube-receiving channel issubstantially semi-circular in the direction perpendicular to saidbending plane.
 12. The apparatus of claim 9, wherein each said dividedportion comprises a portion of said tube-receiving channel.
 13. Theapparatus of claim 9, wherein said tube-receiving channel is annular.14. The apparatus of claim 9, said tube bending apparatus furthercomprising an exterior bending die, wherein said interior bending diecooperates with said exterior bending die during the bending operation.15. The apparatus of claim 14, said tube bending apparatus furthercomprising an exterior bending die comprising a tube-receiving channelsubstantially semi-circular in the direction perpendicular to saidbending plane, said interior bending die further comprising atube-receiving channel substantially semi-circular in the directionperpendicular to said bending plane, wherein said interior bending diecooperates with said exterior bending die during the bending operationsuch that the combination of said exterior bending die tube-receivingchannel and said interior bending die tube-receiving channel completelyencircles said tube.
 16. The apparatus of claim 9, further comprisingmeans to secure and align said divided portions of said interior bendingdie to each other.
 17. The apparatus of claim 16, wherein said securingand aligning means comprises an insert member disposed in one of saiddivided portions and an insert cavity disposed in the other of saiddivided portions, said insert member being received by said insertcavity when said divided portions are adjoining.
 18. A tube-bending diecomprising a tube-receiving channel and a pair of flanges, wherein saidtube-bending die can be separated into two divided portions, eachdivided portion comprising one of said flanges and a portion of saidtube-receiving channel, wherein said tube-bending die is mounted onto ashaft, and wherein at least one of said divided portions can be movedaxially on said shaft to release a tube.
 19. The apparatus of claim 18,wherein said tube-receiving channel is substantially semi-circular inthe direction perpendicular to said bending plane.
 20. The apparatus ofclaim 18, further comprising means to secure and align said dividedportions of said tube-bending die to each other, said securing andaligning means comprising an insert member disposed in one of saiddivided portions and an insert cavity disposed in the other of saiddivided portions, said insert member being received by said insertcavity when said divided portions are adjoining.